Determine the pH of a 1x10^-4 M solution of HCl.
HCl is a strong acid that dissociates completely in water, so it will release H+ ions.
The concentration of H+ ions in the solution will be the same as the concentration of HCl, which is 1x10^-4 M.
pH is defined as the negative logarithm (base 10) of the H+ concentration.
Therefore,
pH = -log[H+]
= -log(1x10^-4)
= -(-4)
= 4
So, the pH of a 1x10^-4 M solution of HCl is 4.